I love our Texas Parks, but their handling of volunteer hosts is pretty lousy. We have friends who have been very successful in getting host positions in the Texas system. They tell me that the way to do it is to pick the park you are interested in, and then make a personal contact with the park manager or their designated volunteer coordinator. That can be either in person or by phone. Explain your interest and ask if you can send the application directly to them. They prefer to make a personal visit, but sometimes that's not easy. They have good references, both personal and from prior host jobs, and they can pretty well get any that they want. The key is the personal contact, not just sending an application and waiting for a response. Be proactive.
By the way, there is a wide disparity in how the various parks treat their hosts. Some provide great sites, and good working conditions, others, not so much. Seems like that depends on the park manager and how they view the volunteers. Talking to the manager helps to decide if you want the position as much as it does help them to decide if they want you.
Good luck!
